At my job as a paint mixer, one of our best part-timers was an old guy named Pete. He used to be an electrician, but "retired" to something I assume was less stressful. When he was first hired, one of the managers there gave me the wrong impression that Pete wasn't going to work out. Something about his attitude, but that manager eventually got fired and he was a giant douchebag, so never take anyone's word for anything.
I trained Pete a great bit and I remember seeing him struggle during his first month. One time we were slammed and I had to go to lunch. The same couple was still there when I came back an hour later. Let's just say it wasn't a good night. He also would make some stupid mistakes that he should have known better not to do when it came to making paint.
But later, he got a lot better and was eventually one of our best people. He also had a great attendance record, I could only recall him being out just once for the three-ish years he worked for us. But one day, our old vendor (who is now a manger for a competitor) called him and offered him something part time from Monday to Friday at the hours of the day he wanted. He left, and never looked back with regret. While I do miss having him, I am happy for him.